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PubMed1997

Use of hydroxyapatite for reconstruction after surgical removal of intraosseous hemangioma in the zygomatic bone.

Two rare cases of intraosseous hemangiomas in the zygomatic bone that were repaired after surgical removal of the tumor with hydroxyapatite implants are reported. Case 1 is a 42-year-old woman, and case 2 is a 46-year-old man. They complained of swelling in the right cheek. An intraosseous tumor in the right zygomatic bone was observed in both patients. The tumor was resected, and hydroxyapatite was employed to repair the defect caused by removal. After 4 years since the operation in case 1 and 8 months in case 2, the patients show satisfactory cosmetic appearance. Hydroxyapatite implant was useful for reconstruction of the defect after surgical removal of hemangiomas in the zygomatic bone.

Adult↗
PubMed1999

Treatment of large complex cranial bone defects by using hydroxyapatite ceramic implants.

Hydroxyapatite ceramic implants were used in the reconstruction of very large and complex-form cranial bone defects in nine patients. The bone defects were the result of craniectomy after infections and other complications such as severe brain edema, after neurosurgery, and as a result of trauma, subdural hemorrhage, and surgery for brain tumor. The size, shape, and curvature of the hydroxyapatite ceramic implants were determined based on high-precision, full-scale models fabricated through a laser lithographic molding method by using computed tomographic data. The use of this method allowed the fabrication of hydroxyapatite ceramic implants of shapes that accurately matched the area of bone defect, allowing for a minimum of adjustment during the operation even with a complex-form implantation. Not only were good cranial contour reconstructed and aesthetically satisfactory results obtained in the cases treated by incorporating this series of techniques, but neurologic conditions present in some cases were also improved to some extent. The postoperative course has been steady for all nine patients, with no blood transfusions required during or after the operations and no implants requiring removal because of infection or other postoperative complications. The average length of postoperative hospitalization for the nine cases was 11.7 days, remarkably short considering the clinical conditions.

Aged↗
PubMed1999

The use of hydroxyapatite cement in secondary craniofacial reconstruction.

Sixty-one patients underwent secondary craniofacial reconstruction for contour defects using hydroxyapatite cement over a 3-year period (20-month mean follow-up). There were 56 children, aged 2.2 to 18 years (mean, 10.7 years), 21 boys and 35 girls. This is the first series of pediatric patients in whom the use of hydroxyapatite cement has been reported. There were five adults aged 21 to 46 years (mean, 32 years), 3 men and 2 women. Thirty-one patients underwent reconstruction for secondary orbitocranial defects after surgery for synostosis, 7 after surgery for hypertelorism, 10 for posttraumatic skull defects, and 13 for a variety of other facial skeletal defects. There were seven complications (11 percent), ranging from a retained drain to postoperative seromas, all of which required reoperation without loss of the contour correction. All of the complications occurred in the first 18 months of our study. There has been excellent retention of implant volume with no recurrence of contour defects to date. We have not found any visible evidence of interference with craniofacial growth over the study period. We conclude that hydroxyapatite cement is a versatile and safe biomaterial when used for the correction of secondary craniofacial contour defects in children and adults. The coupling of antibiotics with this biomaterial may have applications in the treatment of osteomyelitis.

Adolescent↗
PubMed1994

Anterior cervical discectomy and fusion using a porous hydroxyapatite bone graft substitute.

OBJECTIVES: This study analyzed the use of a coral hydroxyapatite bone substitute for use in ACDF both with and without an anterior cervical plate. STUDY DESIGN: The healing of multilevel anterior cervical fusions was tested using a goat model. Comparisons were drawn with histologic, radiographic, and biomechanical test data. METHODS: Forty-nine mature alpine goats had three-level anterior discectomies performed. Seven treatment groups of seven goats each were used; Group I with no fusion, Group IIa having tricortical iliac crest autograft, Group IIb having autograft plus an anterior plate, Group IIIa having tricortical iliac crest fresh-frozen allograft, Group IIIb having allograft plus an anterior plate, Group IVa having rectangular-shaped implants of porous hydroxyapatite, and Group IVb having ProOsteon 500 implants with an anterior cervical plate. RESULTS: Histologically, at 12 weeks 48% of the ProOsteon (Interpore, Irvine, CA) implants were rated as incorporated, 10% as possessing a fibrous gap, 29% as collapsed, and 14% as extruded. Anterior cervical plating improved the results with 71% of the implants showing good incorporation, 24% with collapse, and 5% with a fibrous gap. These histologic results compare favorably with autogenous bone and are improved over allograft bone. Fluorochrome analysis showed that none of the implants had complete turnover with host bone, but that all possessed peripheral creeping substitution with cutting cones of new bone formation at 12 weeks. Biomechanically, the spines using the ProOsteon implant were less stiff in torsion than autograft, but equal in stiffness to allograft. Flexion-extension neutral zone stiffness was lower in the ProOsteon implant group than either allograft or autograft. CONCLUSIONS: The use of a coral-based hydroxyapatite bone graft substitute for anterior cervical fusions led to significant rates of implant collapse at 12 weeks but showed excellent biologic compatibility with good early creeping substitution of the implant by host bone. The concomitant use of an anterior cervical plate with the implant prevents extrusion.

Animals↗
PubMed1996

Evaluation of the surface integrity of hydroxyapatite-coated threaded dental implants after insertion.

The surface characteristics and changes of hydroxyapatite-coated threaded dental implants after insertion into bone (veal calf ribs) with similar cortical and medullary characteristics to the human maxilla and posterior mandible (type III or IV bone) were studied. Hydroxyapatite-coated threaded implants from six vendors were coded A, B, C, D, E, and F. Four implants from each vendor were subjected to conventional placement following the manufacturer's instructions, placement without tapping of the osteotomy site, or evaluated as controls. The implants were recovered atraumatically and examined by scanning electron microscopy at x 35 and x 100 magnification. Photomicrographs were examined and graded by two independent examiners. Statistically significant differences were found using Kruskal-Wallis ANOVA and Wilcoxon Signed Ranks tests in surface integrity between conventional and nontapped treatment for groups C and D; between conventional placement and controls for groups A, B, and F; between nontapped placement and controls for groups A, B, C, D, and E; and among the manufacturers with respect to conventional placement for groups A, B, and E as compared with the other groups (P < 0.05). These findings suggest that surface changes of hydroxyapatite-coated threaded implants may occur during placement, particularly in undersized and untapped osteotomy sites. The changes could result in differences in integration and performance of some implant systems.

Analysis of Variance↗
PubMed1997

Postmortem histologic evaluation of hydroxyapatite-coated cylinder and titanium alloy basket implants in situ for 37 months in the posterior mandible. Dental Implant Clinical Research Group.

Histologic examination of the tissues surrounding a titanium alloy basket implant and a hydroxyapatite-coated titanium cylinder implant from the mandible of a cadaver were examined. The 67-year-old man died 37 months after first-stage surgery from cardiovascular failure. Clinical and radiographic examinations indicated that the implants were functional, immobile, and integrated. Light microscopy revealed that the gingival tissues adjacent to the implants were healthy and, in general, free of inflammatory cells. The transmucosal area demonstrated a tight connective tissue apposition to the implants. The sulcular epithelial appearance was similar to that of a natural tooth. Histomorphometric analysis revealed that 72.2 percent of the basket implant and 75.3 percent of the hydroxyapatite-coated implant were in direct contact with bone. Generally, the bone along the surface of the basket implant was thicker than the bone along the surface of the hydroxyapatite-coated cylinder. Bone grew through the vent hole areas of both implants.

Aged↗
PubMed2006

Early failure of hemispheric hydroxyapatite-coated acetabular cups.

UNLABELLED: Total hip arthroplasties with hydroxyapatite coatings have shown encouraging results after early-term followup. We presumed hydroxyapatite-coating on a smooth hemispheric press-fit acetabular cup would enhance bone osseointegration and maintain stability of cup after midterm (minimum 5-year) followup. Sixty-three patients had 70 consecutive total hip arthroplasties. Five patients (eight hips) died from problems unrelated to surgery. The remaining patients (62 hips) were followed up for an average of 7 years (range, 6-9 years). The mean age of the patients was 49 years (range, 23-61 years). The average Harris hip score improved from 59 points (range, 32-82 points to 82 points (range, 37-100 points) at final followup. There were seven acetabular component revisions. Of the 55 unrevised cups, 47 hips (85%) were stable by bony ingrowth, five hips (9%) were fibrous stable, and three hips (5%) were unstable with cup migration. Osteolysis around the cup was observed in 18 hips (33%). The average polyethylene wear rate was 0.15 mm/year. Survival rates of the cups at 6 and 8 years were 94.3% and 60.5%, respectively. Total hip arthroplasties using an hydroxyapatite-coated smooth hemispheric acetabular cup showed an unexpected high failure rate in terms of fixation, occurrence of osteolysis, and revision after midterm followup. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Acetabulum↗
PubMed2006

Hydroxyapatite-coated femoral components: 15-year minimum followup.

Hydroxyapatite-coated femoral components were introduced to enhance fixation, but concerns were raised about whether the coating would be maintained over time. We therefore determined the long-term clinical and radiographic results of a proximally hydroxyapatite-coated femoral component and compared the mechanical failure rate to other fixation methods at similar lengths of followup. The study group, culled from a large, multicenter prospective study population, consisted of 146 patients (166 hips) with followup of 15 to 18 years. Average age at time of the index procedure was 51 years, and the most common diagnoses were osteoarthritis (71%) and osteonecrosis (11%). Average Harris hip scores were 42.7 preoperatively and 91.5 at most recent followup. Radiographically, one stem showed stable fibrous fixation, and all other unrevised stems were bony stable. Of 13 stem revisions in the study population, only one stem has been revised for aseptic loosening. Forty-nine percent of hips have an osteolytic lesion in proximal areas of Gruen Zones 1, 7, 8, or 14 only. Both the femoral aseptic revision and mechanical failure rates are 0.6% at 15-year minimum followup. The data demonstrate excellent long-term survivorship of this hydroxyapatite-coated femoral component used in a relatively young patient group.

Adolescent↗
PubMed2003

Biomechanical evaluation of cervical double-door laminoplasty using hydroxyapatite spacer.

STUDY DESIGN: In vitro three-dimensional kinematic changes after double-door cervical laminoplasty, with and without spacer, and laminectomy were studied in a human cadaveric model. OBJECTIVES: To evaluate the effects of multilevel double-door laminoplasty and laminectomy as compared with the intact and to assess the influence of the spinous process spacer on the stability of the cervical spine. SUMMARY OF BACKGROUND DATA: Double-door type cervical laminoplasty has been widely used in the treatment of multisegmental stenotic conditions. However, its biomechanical advantages over laminectomy remain controversial. Also, the biomechanical effects of spacers between the split laminae have not been investigated. METHODS: Using fresh cadaveric C2-T1 specimens, sequential injuries were created in the following order: intact, double-door laminoplasty (C3-C6) with insertion of hydroxyapatite spacers, laminoplasty without spacer, and laminectomy. Motions of each vertebra in each injury status were measured in six loading modes: flexion, extension, right and left lateral bending, and right and left axial rotation.RESULTS Cervical laminectomy showed significant increase in motion compared with intact control in flexion [25% (P < 0.001)], extension [19% (P < 0.05)], and axial rotation [24% (P < 0.001)] at maximum load. Double-door laminoplasty with hydroxyapatite spacer indicated no significant difference in motion in all loading modes compared with intact. Laminoplasty without spacer showed intermediate values between laminoplasty with spacer and laminectomy in all loading modes. Initial slack of each injury status showed trends similar to that of maximum load, although mean percent changes of laminectomy and laminoplasty without spacer were greater than that of maximum load. CONCLUSIONS: Double-door laminoplasty with hydroxyapatite spacer appears to restore the motion of the decompressed segment back to its intact state in all loading modes. The use of HA spacers well contributes to maintaining the total stiffness of cervical spine. In contrast, laminectomy seems to have potential leading postoperative deformity or instability.

Adult↗
PubMed2006

The treatment of acute thoracolumbar burst fractures with transpedicular intracorporeal hydroxyapatite grafting following indirect reduction and pedicle screw fixation: a prospective study.

STUDY DESIGN: Prospective consecutive series. OBJECTIVE: To evaluate the outcomes of the treatment of acute thoracolumbar burst fractures by transpedicular hydroxyapatite grafting following indirect reduction and pedicle screw fixation. SUMMARY OF BACKGROUND DATA: In the treatment of thoracolumbar burst fractures, the major problem after posterior correction and instrumentation is failure to support the anterior spinal column, leading to the loss of correction of kyphosis and instrumentation breakage. METHODS: There were 15 consecutive patients who had thoracolumbar burst fractures and associated incomplete neurologic deficit. They underwent surgery within 4 days of admission, had their implants removed within 1 year, and were prospectively followed for at least 2 years. Following indirect reduction and pedicle screw fixation, transpedicular intracorporeal hydroxyapatite grafting to the fractured vertebrae was performed. Median operating time was 130 minutes, and median blood loss was 155 g. RESULTS: The neurologic function of all 15 patients improved by at least 1 American Spine Injury Association grade, with 9 (60%) having complete neurologic recovery. Sagittal alignment was improved from a median preoperative kyphosis of 20 degrees to -1 degrees (lordosis) by surgery but was found to have slightly deteriorated to 1 degrees at final follow-up observation. Computerized tomography showed a median spinal canal narrowing of 64%, 22%, and 11%, respectively. There were no instances of instrumentation failure. CONCLUSIONS: Posterior indirect reduction, transpedicular hydroxyapatite grafting, and pedicle screw fixation could provide reliable neurologic improvement in patients with incomplete neurologic deficit, and could prevent the development of kyphosis. This technique does not require fusion to a segment, thereby preserves thoracolumbar motion.

Adolescent↗
PubMedDate not supplied

A novel approach to re-pegging hydroxyapatite implants using bioactive glass.

PURPOSE: To determine if bioactive glass, originally designed for craniomaxillofacial use, can be used effectively for re-pegging of hydroxyapatite orbital implants. METHODS: Over a 2-year period, 3 patients with pegged hydroxyapatite orbital implants and related complications that did not respond to conservative treatment, underwent removal of the implant pegs and/or sleeves. Peg tracts were subsequently filled with bioactive glass. RESULTS: No complications occurred in any case during 3 years of follow-up. After 2 months, 2 patients underwent successful re-drilling of the peg site and insertion of titanium pegs. Both patients were satisfied with the results. The third patient has deferred re-pegging at this time. CONCLUSION: Bioactive glass is effective for refilling old peg tracts and allowing timely re-pegging of hydroxyapatite implants.

Adolescent↗
PubMed1995

Sucrose-dependent accumulation of oral streptococci and their adhesion-defective mutants on saliva-coated hydroxyapatite.

The adhesion and accumulation of oral streptococci on saliva-coated hydroxyapatite was examined in strains representing species that appear in initial plaque (Streptococcus sanguise FC1 and Streptococcus oralis C5) and in more mature plaque (Streptococcus gordonii G9B). Washed cells of strains FC1 and C5 did not attach better to saliva-coated hydroxyapatite than did strain G9B, suggesting that the degree of initial adhesiveness does not alone account for the temporal appearance of these bacteria in dental plaque. Growing cells of each strain were also examined for their ability to accumulate on saliva-coated hydroxyapatite. The addition of sucrose to the medium promoted the accumulation of strain G9B more than it promoted the accumulation of strains FC1 and C5. Sucrose also enhanced the accumulation of adhesion-defective mutants of each strain to levels similar to those of the respective parent strains. These results suggest that sucrose-dependent accumulation may facilitate the colonization of the tooth surface by these species of oral streptococci when adhesion is limited by reduced bacterial adhesiveness or limited pellicle-binding sites.

Bacterial Adhesion↗
PubMed2001

Role of Streptococcus gordonii amylase-binding protein A in adhesion to hydroxyapatite, starch metabolism, and biofilm formation.

Interactions between bacteria and salivary components are thought to be important in the establishment and ecology of the oral microflora. alpha-Amylase, the predominant salivary enzyme in humans, binds to Streptococcus gordonii, a primary colonizer of the tooth. Previous studies have implicated this interaction in adhesion of the bacteria to salivary pellicles, catabolism of dietary starches, and biofilm formation. Amylase binding is mediated at least in part by the amylase-binding protein A (AbpA). To study the function of this protein, an erythromycin resistance determinant [erm(AM)] was inserted within the abpA gene of S. gordonii strains Challis and FAS4 by allelic exchange, resulting in abpA mutant strains Challis-E1 and FAS4-E1. Comparison of the wild-type and mutant strains did not reveal any significant differences in colony morphology, biochemical metabolic profiles, growth in complex or defined media, surface hydrophobicity, or coaggregation properties. Scatchard analysis of adhesion isotherms demonstrated that the wild-type strains adhered better to human parotid-saliva- and amylase-coated hydroxyapatite than did the AbpA mutants. In contrast, the mutant strains bound to whole-saliva-coated hydroxyapatite to a greater extent than did the wild-type strains. While the wild-type strains preincubated with purified salivary amylase grew well in defined medium with potato starch as the sole carbohydrate source, the AbpA mutants did not grow under the same conditions even after preincubation with amylase. In addition, the wild-type strain produced large microcolonies in a flow cell biofilm model, while the abpA mutant strains grew much more poorly and produced relatively small microcolonies. Taken together, these results suggest that AbpA of S. gordonii functions as an adhesin to amylase-coated hydroxyapatite, in salivary-amylase-mediated catabolism of dietary starches and in human saliva-supported biofilm formation by S. gordonii.

Adhesins, Bacterial↗
PubMed1994

Problems with the hydroxyapatite orbital implant: experience with 250 consecutive cases.

The coral derived hydroxyapatite sphere is a popular, integrated orbital implant designed to provide improved motility of the ocular prosthesis following enucleation. Although the implant has rapidly become widely used by ophthalmologists, little information is available regarding the problems of this technique in a large series of cases. Experience with 250 consecutive cases of hydroxyapatite orbital implant use was reviewed and the problems of the implants and their management investigated specifically. The reasons for enucleation included uveal melanoma (157 cases), retinoblastoma (70 cases), blind painful eye (22 cases), and intraocular medulloepithelioma (one case). Earlier treatment to the eye was performed before enucleation in 47 cases and included repair of ruptured globe (17 cases), plaque radiotherapy (18 cases), external beam radiotherapy (six cases), and others (six cases). During a mean of 23 months' follow up (range 6-40 months), there have been no recognisable cases of orbital haemorrhage related to the implant, and no cases of implant extrusion or implant migration. There was one case of presumed orbital infection (culture negative) that resolved with intravenous antibiotics and the implant was retained within the orbit. Other problems included conjunctival thinning in eight cases managed by observation and prosthesis adjustment, and conjunctival erosion in four cases managed by combinations of scleral patch graft, conjunctival flap, and prosthesis adjustment. The conjunctival erosion was caused by a poorly fitting prosthesis in three cases and wound dehiscence in one case. The problem rate in eyes receiving prior radiotherapy or surgery was not increased. The hydroxyapatite integrated orbital implant is a well tolerated motility implant without the high rate of extrusion and infection seen with other motility implants. The prosthesis fit may contribute to the tolerance of the implant.

Child↗
PubMedDate not supplied

A morphological study of drill holes applied with mitomycin-C in hydroxyapatite orbital implants.

For maximum motility of the prosthesis, the hydroxyapatite orbital implant should be drilled and coupled to the prosthesis via a motility peg. However, problems of peg extrusion have been reported to occur in 25-30% of cases. In this animal study, serial histopathological changes within the drill hole after hydroxyapatite implantation were observed and the effect of mitomycin-C (MMC) was evaluated as a new method of hole maintenance. A hole was drilled into each hydroxyapatite implant 20 weeks after enucleation and different concentrations of MMC solution were applied. The morphological changes of the holes were evaluated with proliferating cell nuclear antigen. In the control group (non-MMC-treated), all the motility pegs were extruded showing occluded holes. In the groups treated with 0.5 and 1.0 mg/ ml MMC, all the motility pegs were maintained in position with the holes at ample depth and width. However, toxicity, such as conjunctival ulcer and implant exposure around the hole, was observed in the 1.0 mg/ml MMC group. A 0.5 mg/ml MMC application for 5 min to the drill hole effectively reduced the risk of peg extrusion in this albino rabbit model.

Animals↗
PubMed1995

Modification of the scleral openings to reduce tissue breakdown and exposure after hydroxyapatite implantations.

We compared the incidence of exposure of the hydroxyapatite implant after evisceration according to the position of scleral windows which allow rapid fibrovascularization into the implant. Three patients (10%) developed tissue breakdown and exposure of the hydroxyapatite, out of 30 patients who had external scleral windows located in a position just anterior to the insertion of each of the rectus muscles, whereas no patient developed exposure, out of 24 patients who had internal scleral windows located in a position just position just posterior to the insertion of each of the rectus muscles. Internal windows sealed with rectus muscles could prevent direct contact between implant and the overlying Tenon's capsule and conjunctiva. These findings seem to indicate that the rough spicular surface of the hydroxyapatite irritates and erodes the overlying Tenon's capsule and conjunctiva.

Biocompatible Materials↗
PubMed2001

Characterization of bone cements prepared with functionalized methacrylates and hydroxyapatite.

Bone cements prepared with methyl methacrylate and either methacrylic acid or diethyl amino ethyl methacrylate as comonomers were characterized by infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, dynamic mechanical thermal analysis, and mechanical testing. Selected formulations containing these functionalized methacrylates were filled with hydroxyapatite and studied in terms of their properties in tension, compression and bending, and X-ray diffraction. It was found that residual monomer was not greatly affected by the presence of either acid or basic comonomers in the unfilled bone cements. In contrast, molecular weight, curing times, and glass transition temperature were composition dependent. For samples with acidic comonomer, a faster curing time, higher molecular weight, and higher glass transition temperatures were observed with respect to those with the basic comonomer. X-ray diffraction revealed that the crystalline structure was not affected by the nature of comonomer in the bone cement while scanning electron microscopy showed that hydroxyapatite remained as clusters in the bone cement. The mechanical properties of filled bone cements depended mainly on composition and type of testing. Hydroxyapatite-filled bone cements fullfilled the minimum compressive strength (70 MPa) required for bone cement use. However, the minimum tensile strength (30 MPa) was only fullfilled by cements prepared without comonomer and those containing methacrylic acid. The minimum bending strength requirement (50 MPa) was not satisfied by any of the formulations studied.

Biocompatible Materials↗
PubMed1995

Bacterial colonization on titanium, hydroxyapatite, and amalgam surfaces in vivo.

A study was conducted to evaluate qualitative and quantitative differences in bacterial colonization on titanium, hydroxyapatite, and amalgam surfaces in vivo. Six healthy adult individuals participated in the study. Two pieces each of titanium, hydroxyapatite, and amalgam of similar size were placed in cobalt-chromium splints and kept intra-orally in each individual for 10 min, and 1, 3, 6, 24, and 72 hrs. After removal of the splints, the pieces were rinsed in PBS and transferred to transport medium. After being vortexed, the samples were inoculated on selective and non-selective media for analyses of various facultative and anaerobic bacteria. During the experiment, total viable count increased on all surfaces. The investigated bacterial groups constituted, on average, approximately 60 to 99% of the total viable count on all three types of surfaces in each of the experiments, except in the 10-minute samples, when they constituted around 20 to 30%. Various streptococcal species predominated and usually constituted > 50% of total viable count. Similar colonization patterns of Streptococcus spp., Actinomyces naeslundii, Neisseria spp., Hemophilus parainfluenzae, Fusobacterium spp., and black-pigmented Prevotella spp. were seen at all three types of surfaces. No significant differences among the materials regarding colonization of investigated bacteria were found during the study period. This study failed to show any qualitative and quantitative differences in bacterial colonization among these materials. Titanium, hydroxyapatite, and amalgam do not seem to have a marked influence on the early colonization pattern in vivo.

Adult↗